eBGP Physical Peering on Cisco IOS-XR

conceptYaakkkk…… EBGP Peer on Cisco IOS-XR. Agak beda dikit disini woi sama di cisco IOS based. Pertama kali konfig EBGP di IOS-XR “loh.. kok state/prefixreceivnya !0???!! ehhh usut punya usut ada yang beda EBGP peering di IOS-XR. What is that? cekidott… 🙂

Di IOS-XR default policy buat EBGP ternyata drop coy!! nggak kayak di IOS yang allow all, jadi prefix yang mau di exchange antara neighbor A dg neighbor B itu defaultnya di drop semua!! (set dah). Tapi sebenernya lebih bagusan defaultnya drop juga sih kalo di dunia nyata (menurutku). Jadi ketika peer ebgp kita musti define mana aja prefix yang boleh masuk (diterima) sama prefix mana aja yang bakal diadvertise (dikirim), ato kalo agak males-malesan yaa allow all aja…haha… Kenapa begitu?? dengan begini akan memaksa Net Admin buat bener-bener nentuin mana aja yang bakal di advertise dan diterima, jadi nggak sembarangan lagi. Ingat kasus route leak alias kebocoran routing di internet yang mampu mengacaukan jaringan internet? nah ini salah satu contoh kurang berhati-hatinya dalam mainan advertise, mangkanya di IOS-XR setidaknya kita dipaksa buat lebih teliti…hehe…

Ok mari Lab 🙂 Topologi yang dipake nerusin topologi BGP sebelumnya, dibuat beda dikit di ASN doang..haha…

topoSkenarionya, antara R1 dan R2 adalah IBGP dengan ASN4800, R2 Peering ke R3 pake Physical IP, hasil akhirnya semua ip loopback maupun fisik reachable dari R1-R3, dah gitu aja 🙂 Basic Peering dah pernah dibahas, gampang dah, kalo lupa, buka aja post sebelumnya. Disini ane tekanin di EBGP Peering aja.

Let’s go to R2 & R3 cfg. Let see R2 cfg first..

1 r2 cfgKonfig seperti biasa, tidak ada yang spesial 🙂 let’s move to R3 cfg

2 r3 cfgNothing special too, in IOS based this config should word, right?? but let’s check in IOS-XR, is it will work like in IOS??

(1) sh bgp summ – cek state neighborship…

3 r3 sh bgp sum

(2) routing table

4 r3 sh route

(3) sh ip bgp5 r3 sh ip bgp

St/PrxRcd is 0!, belom masuk ke routing table, ip bgp masih kosong, wadafaq, wad hapen?? :v wadis wrong??! Mari kita cek lebih dalem di Neighborshipnya

6 sh neiYap, that is i mean, default policy for eBGP neighbor is “DROP”!! so we have to create a policy and apply it to eBGP Neighbor policy to allow inbound and outbound bgp route updates. In IOS we use route-map, but in IOS-XR we will not find route-map again. In IOS-XR route-map feature replaced with RPL (Routing Programming Language). It’s so like programming with “if-then concept”. Let’s make basic RPL to allow any and apply it to inbound & outbond EBGP policy in R2 and R3. You have to create rule like this in Border Gateway Router for EBGP Peering on Cisco IOS-XR based.

7 create policyLet’s check again the routing table and ip BGP in R3 (R3 and R3 are similar in this case, i just showing R3 in this post).

8 r3 res ip bgp

9 sh routeYeay… ip bgp in, routing table in 🙂 last procedure (ceileh procedure) let’s try it’s connectivity. I will try to ping from R3 to R1. cekidott…

10 test pingOkay, that fine. end-to-end already connected, you can make sure the connectivity by ping on every source to every destination on topologi…haha… The important point in this lab is about “default policy” in EBGP Peer on IOS-XR, watch up about it!!! 🙂

 

 

 

 

 

 

 

 

 

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